Will code in a Finally statement fire if I return

Question

I'm reviewing some code for a friend and say that he was using a return statement inside of a try-finally block. Does the code in the Finally section still fire even though the rest of the try block doesn't?

Example:

public bool someMethod()
{
  try
  {
    return true;
    throw new Exception("test"); // doesn't seem to get executed
  }
  finally
  {
    //code in question
  }
}

Answer 1

Yes. That is in fact that main point of a finally statement. Unless something catestrophic occurs (out of memory, computer unplugged, etc.) the finally statement should always be executed.

Answer 2

I realize I'm late to the party but in the scenario (differing from the OP's example) where indeed an exception is thrown MSDN states (https://msdn.microsoft.com/en-us/library/zwc8s4fz.aspx): "If the exception is not caught, execution of the finally block depends on whether the operating system chooses to trigger an exception unwind operation."

The finally block is only guaranteed to execute if some other function (such as Main) further up the call stack catches the exception. This detail is usually not a problem because all run time environments (CLR and OS) C# programs run on free most resources a process owns when it exits (file handles etc.). In some cases it may be crucial though: A database operation half underway which you want to commit resp. unwind; or some remote connection which may not be closed automatically by the OS and then blocks a server.

Answer 3

Yes Finally call .

  public static bool someMethod()
    {
        try
        {

            return true;
            throw new Exception("test"); // doesn't seem to get executed
        }
        finally
        {
            //code in question
        }
    }

Answer 4

Quoting from MSDN

finally is used to guarantee a statement block of code executes regardless of how the preceding try block is exited.

Answer 5

There's a very important exception to this which I haven't seen mentioned in any other answers, and which (after programming in C# for 18 years) I can't believe I didn't know.

If you throw or trigger an exception of any sort inside your catch block (not just weird StackOverflowExceptions and things of that ilk), and you don't have the entire try/catch/finally block inside another try/catch block, your finally block won't execute. This is easily demonstrated - and if I hadn't seen it myself, given how often I've read that it's only really weird, tiny corner-cases that can cause a finally block not to execute, I wouldn't have believed it.

static void Main(string[] args)
{
    Console.WriteLine("Beginning demo of how finally clause doesn't get executed");
    try
    {
        Console.WriteLine("Inside try but before exception.");
        throw new Exception("Exception #1");
    }
    catch (Exception ex)
    {
        Console.WriteLine($"Inside catch for the exception '{ex.Message}' (before throwing another exception).");
        throw;
    }
    finally
    {
        Console.WriteLine("This never gets executed, and that seems very, very wrong.");
    }

    Console.WriteLine("This never gets executed, but I wasn't expecting it to."); 
    Console.ReadLine();
}

I'm sure there's a reason for this, but it's bizarre that it's not more widely known. (It's noted here for instance, but not anywhere in this particular question.)

Answer 6

Here's a little test:

class Class1
{
    [STAThread]
    static void Main(string[] args)
    {
        Console.WriteLine("before");
        Console.WriteLine(test());
        Console.WriteLine("after");
    }

    static string test()
    {
        try
        {
            return "return";
        }
        finally
        {
            Console.WriteLine("finally");
        }
    }
}

The result is:

before
finally
return
after